chore: conversation list loading improvements [WPB-21750]

[Garzas]

WPB-21750 [Android] Investigate performance improvements for loading conversation list on clients with a lot of history and in general

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• The PR Title

  • conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
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What's new in this PR?

Issues

• Rendering the conversation list caused long initial frame times on older Android devices.
• Markdown parsing was executed during recomposition inside LastMessageSubtitle.
• CommonMark parser and InlineParser were visible in measure and recompose in the profiler.
• Initial paging load was too large, causing heavy mapper work at startup.
• Search flow could block on first collect due to missing onStart.

Causes

• LastMessageSubtitle called toMarkdownDocument and getFirstInlines for every recomposition.
• Markdown parsing is CPU heavy and should never run on the UI thread.
• UILastMessageContent did not store any precomputed markdown representation.
• LazyPagingConfig loaded 60 items on first load, causing unnecessary work.
• A flow in the view model suspended until initial value, delaying recomposition.

Solutions

• Added markdownPreview field to UILastMessageContent.TextMessage and SenderWithMessage.
• Precomputed MarkdownPreview inside mappers using UIText.toMarkdownPreviewOrNull.
• LastMessageSubtitle now prefers the provided markdownPreview and falls back only when null.
• This ensures no markdown parsing happens inside Compose.
• Reduced initial paging load size from 60 to 40 to reduce mapper pressure on first frame.
• Added onStart to isSelfUserUnderLegalHoldFlow to avoid delaying combine.

[github-actions]

@Garzas looks like you are rolling back kalium to a previous commitish.

This means that the PR's target branch (develop) is using a newer version of Kalium, and the changes in this PR will rollback Kalium to an older version.

develop	This PR
a7dbd73f9efcd1b2d0322cf113f1d46fe0209d8d	e520bb68d7abe5b8d2e82afd4f8f4f5141fd704e

Is this intentional?

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud